function xnstHipLenFn = nstHipLenFn(x)
xnstHipLenFn = sqrt(((2261*cos(x(1) + x(2) + x(3)))/5000 +  ...
    (1903*cos(x(1) + x(2) + x(3) - x(4)))/5000)^2 +  ...
  ((-2261*sin(x(1) + x(2) + x(3)))/5000 -  ...
    (1903*sin(x(1) + x(2) + x(3) - x(4)))/5000)^2) ...
;